4.1 - Waves and quantum behaviour (A-Level Physics OCR B H557)

#4.1a(i)

production of standing waves by waves travelling in opposite directions

Including graphical treatment

#4.1a(ii)

interference of waves from two slits

#4.1a(iii)

refraction of light at a plane boundary in terms of the changes in the speed of light and explanation in terms of the wave model of light

#4.1a(iv)

diffraction of waves passing through a narrow aperture

#4.1a(v)

diffraction by a grating

#4.1a(vi)

evidence that photons exchange energy in quanta $E = hf$ (for example, one of light-emitting diodes, photoelectric effect and line spectra)

*limitations of particle and wave models *

#4.1a(vii)

quantum behaviour: quanta have a certain probability of arrival; the probability is obtained by combining amplitude and phase for all possible paths

#4.1a(viii)

evidence from electron diffraction that electrons show quantum behaviour.

#4.1b

Make appropriate use of:

(i) the terms: phase, phasor, amplitude, probability, interference, diffraction, superposition, coherence, path difference, intensity, electronvolt, refractive index, work function, threshold frequency.

#4.1c(i)

wavelength of standing waves

end corrections not required

#4.1c(ii)

Snell’s Law, $n = \dfrac{\sin{i}}{\sin{r}} = \dfrac{C_{\text{1st medium}}}{C_{\text{2nd medium}}}$

#4.1c(iii)

path differences for double slits and diffraction grating, for constructive interference $nλ = d\sin{θ}$ (both limited to the case of a distant screen)

angles may be given in degrees or radians, the use of the small angle approximation is expected.

#4.1c(iv)

the energy carried by photons across the spectrum, $E = hf$

#4.1c(v)

the wavelength of a particle of momentum p, $λ = \dfrac{h}{p}$

As given by the de Broglie relationship

#4.1d(i)

using an oscilloscope to determine frequencies

links to 4.1a(i), PAG5

#4.1d(ii)

determining refractive index for a transparent block

links to 4.1c(ii), PAG6

#4.1d(iii)

superposition experiments using vibrating strings, sound waves, light and microwaves

links to 4.1a(i), b(i), c(i), PAG5

#4.1d(iv)

determining the wavelength of light with a double-slit and diffraction grating

links to 4.1a(ii), a(v), c(iii), PAG5

#4.1d(v)

determining the speed of sound in air by formation of stationary waves in a resonance tube

links to 4.1a(i), c(i), PAG5

#4.1d(vi)

determining the Planck constant using different coloured LEDs.

links to 4.1a(vi), c(iv), PAG6

A-Level Physics OCR B H557

4.1: Waves and quantum behaviour